On a front surface (front end) of a car body in a front car, so as to cover the car body, panel-shaped plastic outer shell end caps (hereinafter, referred to as the “end caps”) are sometimes attached as a decoration. It should be noted that the end caps are sometimes called as the “front hoods or front bonnet”. The car body is a structural element made by metal, and the end caps are often made of Fiber Reinforced Plastics (FRP). Providing a windshield wiper on a front window of the car body allows a driver to ensure visibility at the time of rainfall or the like. A drive unit for the windshield wiper such as a motor is provided inside the car. One end of a wiper shaft of the windshield wiper is connected to the drive unit and the other end is connected to a wiper blade (made by rubber) outside the car. Also, the wiper shaft rotatably passes through the front surface to drive the wiper blade. A through hole section of the wiper shaft in the front surface is required to have a waterproof structure.